Objectives. To review the experience with partial nephrectomy for the diagnosis and treatment of renal cortical tumors at the Memorial Sloan-Kettering Cancer Center with a particular focus on the histologic findings at the time of surgery. Methods. The results of 292 consecutive partial nephrectomies were reviewed. Demographic data, perioperative complications, and disease status were recorded. The specimens were reviewed for histologic subtyping in accordance with the Heidelberg classification for renal cortical tumors. The probabilities of recurrence and disease-specific death were assessed with the cumulative incidence estimate. Results. The median follow-up was 25.3 months (range 1 to 155). A total of 246 patients (87%) were diagnosed with a renal cortical tumor, 1 patient (less than 1%) was diagnosed with another cancer, and 34 (12%) were diagnosed with benign lesions. The most frequent histologic finding among the renal cortical tumor subgroup was conventional clear cell carcinoma in 148 cases (51%), followed by papillary carcinoma in 54 (18%), oncocytoma in 32 (11%), and chromophobe carcinoma in 21 (7%). Bilateral disease and multifocality were most prevalent in the conventional and papillary subtypes, respectively. The 5-year probability of recurrence and disease-specific death was 12% and 8%, respectively, for the conventional clear cell type. No local or distant disease recurrence was observed in any other renal cortical tumor subtypes. Conclusions. Partial nephrectomy should be considered a diagnostic and therapeutic surgical approach for renal cortical masses. Conventional clear cell carcinoma is the most frequent histologic subtype and is associated with a less favorable outcome compared with papillary carcinoma and chromophobe carcinoma. Radical nephrectomy for renal lesions that could be removed by partial nephrectomy will risk renal impairment in a substantial proportion of patients with benign disease.